The present invention relates to a wheel hub for a bicycle, in particular a racing bicycle.
The main target of manufacturers of components for racing bicycles is to reduce the weight of the individual components as much as possible. In the case of wheel hubs, the conventional technology envisages the use of light metal alloys, such aluminium alloys and the like. In order to reduce the weight of wheel hubs, solutions have already been proposed in which a tubular central part of the wheel hub is made of carbon fibres embedded in a resin of plastic material and in which a pair of side shells made of aluminium alloy are driven on the ends of the central portion made of carbon fibres. The side shells are provided with seats for supporting rolling bearings and for anchorage of the wheel spokes. Forming side shells made of carbon fibres in an integral way with the central portion would enable a further weight reduction but would entail serious problems as regards the way in which the spokes are anchored, above all in the case of spokes with L-shaped anchorage portions. If spokes of this sort were connected inside holes formed in a flange made of carbon fibres or the like, the stresses produced by tensioning of the spokes would give rise to contact pressures on the walls of the holes so high as to damage the hub in an irreparable way.
The purpose of the present invention is to provide a wheel hub that may overcome the aforesaid drawbacks.
According to the present invention, the above purpose is achieved by a wheel hub comprising a tubular body having at its ends a pair of flanges, each of which is provided with a plurality of holes for anchorage of respective spokes, in which at least one flange is made of fibre-reinforced plastic material and the aforesaid holes are associated to respective bushings made of metal material, each of which, in use, is set between an anchoring portion of a spoke and the inner wall of the respective hole.